1. Field of the Invention
This invention relates to an electric delay circuit element such as a so-called delay line arranged to delay an electric signal for a predetermined period of time and which is used at various points in a pulse circuit in the fields of electronic computers, electrical communications equipment, and other various electronic applications. More particularly, the present invention pertains to a lumped constant type delay line device.
2. Description of the Prior Art
In order to have a better understanding of the present invention, description will first be made of a conventional lumped constant type delay line device with reference to FIGS. 1 to 3 of the accompanying drawings. The conventional lumped constant type delay line device is constructed by using coils 10 and capacitors 20 as shown in FIG. 1.
FIG. 2 illustrates, by way of example, the construction of such conventional lumped constant type delay line device, prior to encapsulation with a plastic material. More specifically, in the illustrated construction, a plurality of capacitors 20 are soldered to wiring patterns printed on the bottom surface of a printed circuit board 30, and a plurality of coils 10 each wound on a core 40 formed of ferrite, cermics or the like are mounted on the top surface of the printed circuit board 30. Lead wire 12 of the coil 10a at the input end, lead wire 14 of the coil 10b at the output end, and taps of the respective coils 10 are connected, by soldering, to the printed wiring patterns of the printed circuit board 30 and then to terminals 50.
To assemble such delay line device, it has heretofore been the practice to take the following procedures:
First, the coils 10 are continuously wound onto the cores 40; then taps 16 are formed by twisting; and the free ends of the taps 16 are pre-soldered. Meanwhile, capacitors 20 are attached, by soldering, onto the bottom surface of the printed circuit board 30, and the cores 40, which are connected together through the coils 10, are fixed to the top surface of the printed circuit board 30. Subsequently, the lead wires 12, 14 and taps 16 of the coils 10 are led out and soldered to predetermined connection points in the printed wiring patterns.
Thereafter, the printed circuit board 30, which has the coils 10 and capacitors 20 mounted thereon, is placed in such a manner that the terminals 50 can be held between two rows of lead frames (not shown), and the printed wiring patterns are soldered to the terminals 50 at the connection points where the lead wires 12, 14 and taps 16 have been soldered. Unwanted portions of the lead frames are then cut off, and in this way the construction of a delay line device such as shown in FIG. 2 is realized.
However, the above-described conventional construction is disadvantageous in that the taps 16 of the coils 10 must be twisted since they are elongated in the form of loop as shown in FIG. 3, and would otherwise become loose so that difficulty would be experienced in an attempt to solder the taps to the printed wiring patterns, and in a worse case the taps 16 would be cut off or shorted. Another disadvantage is such that difficulty is involved in an attempt to automate the operation of soldering the elongated taps 16 to the predetermined portions of the printed wiring patterns; thus it has heretofore been the practice that such soldering operation is performed manually.